Posit Connect launches R and Python to perform a variety of tasks. This includes:
- Installing R and Python packages
- Rendering reports such as R Markdown and Quarto documents and Jupyter Notebooks
- Running Shiny, Dash, Streamlit, or Bokeh Applications
- Customizing a parameterized R Markdown document
- Running APIs using Plumber, Flask, or FastAPI
The location of R defaults to whatever is in the path. Customize the
R.Executable setting to use a
specific R installation. Python installations are configured by setting
installations are configured by setting
Quarto.Executable. See the
R, Python, and Quarto sections for
Off-Host Execution (Public Beta)
This section about process sandboxing only applies to the "native" execution mode of Posit Connect.
If you are running Posit Connect with off-host Kubernetes execution
(beta), the Posit Connect container does not need to be run as
privileged or with the
CAP_SYS_ADMIN capability. When using off-host
Kubernetes execution, isolation between content items is handled using
separate containers and Kubernetes
VolumeMounts. An overview of this
architecture is in our official feature
The Posit Connect process runs as the
root user. These elevated privileges
let Connect bind to protected ports, manage files and processes for your
RunAs users, and create "unshare" environments where content processes are
Posit Connect uses unprivileged users to run any content process. Content will run using either a system-default user or a content-specific override. See the User Account for Processes section for details. Content processes are also run within an "unshare" environment, which partially isolates those processes.
Posit Connect runs processes within an environment constructed using
unshare(2). Within this environment, a mount namespace (
constructed, which lets Connect create bind mounts with
mount(2) that hide
and isolate parts of the file system from the content process. A user
CLONE_NEWUSER) is created to partially isolate the process.
If you are running Posit Connect within a Docker container using its "native" execution mode, the container must be started with additional privileges. The Docker section discusses privileged containers and the capabilities needed by Posit Connect.
Some systems disable user namespaces by default (e.g. Red Hat Enterprise Linux 7). Content process sandboxes will not include a user namespace on these systems. Enable user namespaces for additional process isolation.
You can use
sysctl to determine if
user.max_user_namespaces is set to
zero, indicating that support is disabled.
These references link to the Linux documentation about namespaces and the system calls used to create the process sandbox.
File system access and isolation#
The following locations are masked during content execution:
Server.DataDirdirectory containing all variable data used by Posit Connect.
SQLite.Dirdirectory, which can optionally be placed outside the data directory.
Configuration directories, including
Server.TempDirdirectory contains a
connect-workspacessub-directory with per-process temporary directories.
The following information is exposed during content execution:
Data directories containing installed packages and environments. The exact set of directories will vary depending on the type of content.
The directory containing the deployed and unpackaged R or Python code.
The document rendering destination directory (only for executable reports).
A directory to receive log files containing process output.
A per-process temporary directory specified in the
TMPDIRenvironment variable of the process. This temporary directory is created under
is enabled, the contents of
/home are masked by an additional bind mount as
- The contents of
/homeare masked by the home directory of the
- If the
RunAsdoes not have a home directory, an empty directory masks
The path to the home directory is always available through the
environment variable. With
the mounted path to the
HOME directory is subject to change. Avoid
hard-coding paths to either
Interactive applications like Shiny, Plumber, Dash, Flask, and FastAPI have write access to the directory containing the unpackaged code. This directory is the working directory when launching an application. Data written into this directory is visible to all processes associated with that application not to processes associated with other content. Application directory data remains available until that application is next deployed to Posit Connect. A deployment creates a new application directory containing only the deployed content.
Posit Connect may launch multiple processes to service requests for an application. There is no coordination between these processes. Applications that write to local files could experience problems when different processes attempt to write to a single file.
For example, two different processes writing to the same file may see output incorrectly interleaved or even overwritten.
We do not recommend using the file system for data persistence.
Executable reports have write access to a directory containing its source code and a separate output directory that receives the rendered result. A new directory containing the deployed source code is created each time the content is executed. This copy of the code ensures that simultaneous rendering processes are isolated from each other and cannot overwrite each other's output files. The temporary source directory is the working directory when rendering the content. A distinct output directory is used each time the content is rendered. Data created during one rendering is not visible to another.
Posit Connect serves rendered content using the results written into the output directory. This result remains available until the next successful render. Incomplete and unsuccessful document renderings do not affect the availability of a previously rendered result.
R Markdown multi-document sites have a slightly different rendering pipeline
than standalone documents. Posit Connect uses the
function, which does its rendering in-place. The content from the source
directory is copied into the rendering destination directory in preparation
for rendering. Site rendering has write access to the destination directory.
Access to the original source directory is not provided because the source
content is duplicated in the destination directory
rmarkdown::render_site call usually places its output into a
_site). The contents of this output subdirectory
will be moved to the root of the rendering destination directory, replacing
any other content. No post-rendering file movement occurs if
rmarkdown::render_site is instructed to render into the current directory
instead of a subdirectory. This means that both source and output files will
be available for serving.
We recommend against configuring
rmarkdown::render_site to write its
output into the current directory. Rendering the site into a subdirectory
(the default) allows Posit Connect to remove source from the output directory.
Posit Connect serves the rendered results for a multi-document site. This result remains available until the next successful render. Incomplete and unsuccessful site renderings do not affect the availability of a previously rendered result.
Each process started by Posit Connect is given its own unique temporary
directory. These directories are created under
The default value for
Server.TempDir is obtained by
first checking the
TMPDIR environment variable for a path and falls back to
You may wish to override
Server.TempDir if the default temporary directory has
too little space or is mounted with the
If you do override
Server.TempDir please ensure the location can be
reached by, read from, and written to by any user on the system. On most
systems, temporary directories typically have permissions of
You can learn more about the
Applications & APIs#
Posit Connect manages both batch-oriented and long-lived processes. Batch-oriented process tend to be narrowly scoped and short-lived, while processes for applications built with web frameworks such as Shiny, Plumber, Flask, FastAPI, Dash, or Streamlit may see a process handle many requests for many users over their lifetimes.
Posit Connect launches a process tied to a live application when the first request arrives for that application. That process will continue to service requests until it becomes idle and is eventually terminated. If there is sufficient traffic against that application, Posit Connect may launch additional processes to service those requests.
There are a number of configuration parameters which control the conditions under which processes for applications are launched and eventually reaped. The default values are appropriate for most applications but occasionally need customization in specialized environments. The Scheduler configuration appendix explains each of the options.
We recommend that adjustment to these runtime properties be done gradually.
User Account for Processes#
RStudio is now Posit
Our professional products have been renamed to Posit Connect, Posit Workbench, and Posit Package Manager. Some references to RStudio and
rstudio-connect will remain as we transition through the rebrand.
Off-Host Execution (Public Beta)
When using off-host execution on Kubernetes, the
Applications.RunAs user may not exist
within the content container. Posit Connect does nothing to provision the user
for you, however, the container will be started with the
uid/gid of the
Applications.RunAs user from the Posit Connect server container.
Posit Connect executes your content with an unprivileged Unix account. The
tells Posit Connect which account to use. The
rstudio-connect account is
created during installation and used as the default value for
root account never executes deployed user code.
Administrators can configure some pieces of content to be executed by a
different Unix account than the
Applications.RunAs default. This setting is
found in the Access tab when editing content settings. Non-administrators
are prohibited from changing the
Each Unix account used as a custom
RunAs must be a member of the Unix group
Applications.SharedRunAsUnixGroup. This group membership requirement
always applies, even when
Applications.RunAs does not use the default
rstudio-connect user has a primary group also named
Let's customize the Unix
RunAs user and
SharedRunAsUnixGroup to allow alternate Unix accounts
for specific pieces of content.
We want to use the
ds-system Unix account as our default
RunAs user and
data-scientists Unix group as our shared group.
The following configuration tells Posit Connect to use
; /etc/rstudio-connect/rstudio-connect.gcfg [Applications] RunAs = "ds-system" SharedRunAsUnixGroup = "data-scientists"
Other Unix accounts that belong to the
data-scientists group can be used as
overrides. For example, the Unix account
hadley must be a member of the
group before it can be used to run your application.
Package installation always happens as the
Applications.RunAs user. An
application or report may override its
RunAs setting; this alters
how the deployed code is executed and does not impact package installation.
See the Sandboxing section for more information about process
RunAs Unix account does not need to be associated with a Posit
Connect user account. Most installations use a small number of shared Unix
accounts. Some configurations (e.g. PAM
authentication) pair Posit Connect user accounts
with Unix accounts, but this is not required.
Licensed user limits are enforced against Posit Connect user accounts, not the Unix accounts used to run content.
Current user execution#
Off-Host Execution (Public Beta)
Applications.RunAsCurrentUser setting is not available when using off-host execution.
Posit Connect can use a local Unix account associated with the currently logged-in user when executing applications. This works for Shiny apps, Shiny documents, and Python Dash, Streamlit, and Bokeh apps. This feature requires that user authentication use PAM.
See Authentication Integration with PAM for information about using PAM for user authentication.
property specifies that content can be configured to execute as the currently
; /etc/rstudio-connect/rstudio-connect.gcfg [Applications] RunAsCurrentUser = true
Content execution settings are not altered when
Applications.RunAsCurrentUser is enabled. The
Applications.RunAsCurrentUser setting permits current-user execution but
by itself does not change how processes are launched. Each application or
interactive document must explicitly request current-user execution.
Applications.RunAsCurrentUser is enabled, administrators can customize
individual content items to run as the Unix account associated with the
logged-in user. The Access content setting tab gives content the option of
executing using "The Unix account of the current user".
Content configured to run as the current-user will execute as the specified
RunAs user when accessed anonymously.
Content without this current-user customization will continue to run as the
See the User Account for Processes section for more information about
All Unix accounts used to execute content must be members of the Unix group defined
Applications are not permitted to launch if the Unix account associated with
the logged-in user does not have the proper group membership.
Applications.RunAs setting uses the
rstudio-connect user by default.
This user has a primary group also named
rstudio-connect. Any Unix account
that may be used to execute content must be a member of the
Off-Host Execution (Public Beta)
PAM sessions are not forwarded to the content container when using off-host execution.
When using PAM for authentication, Posit Connect can leverage PAM to establish the environment and resources available when content runs.
PAM sessions are enabled with the
; /etc/rstudio-connect/rstudio-connect.gcfg [PAM] UseSession = true
The default PAM service name used for PAM sessions is
su. This gives Posit
Connect the ability to launch processes as the specified user without
requiring a password.
You can customize the PAM service name used for PAM sessions by customizing
; /etc/rstudio-connect/rstudio-connect.gcfg [PAM] SessionService = posit-connect-session
PAM.SessionService must contain the PAM directive that enables
authentication with root privileges. Otherwise, processes will not run and
will return error code 70.
# Allows root to su without passwords (required) auth sufficient pam_rootok.so
PAM Credential Caching (Kerberos)#
Posit Connect's PAM cache is encrypted and is not stored on disk. The credentials must expire after a certain period of time.
Posit Connect can be configured to securely cache a user's PAM credentials when they log in to Posit Connect. This enables Posit Connect to let users run processes as their current UNIX account when the PAM profile requires a user's credentials, such as when using Kerberos.
The following config settings are required for credential caching to be enabled:
; /etc/rstudio-connect/rstudio-connect.gcfg [Applications] RunAsCurrentUser = true [PAM] ; Enable PAM sessions UseSession = true ; Forward the current user's password into the PAM session ForwardPassword = true ; Cache passwords for 12 hours after login PasswordLifetime = 12h ; PAM service that accepts credentials ("su" is the default) AuthenticatedSessionService = YOUR_PAM_SERVICE_HERE
12h with the amount of time you would like credentials to be cached.
Credential lifetime is counted from the moment the user logs into Posit
Connect. It is not tied to the user's web session, except that logging in again
will restart the timer for that user's credentials.
setting is similar to
that it should accept user credentials and validate them. For example, a PAM
service that uses the host's Kerberos configuration to expose functionality
auth required pam_krb5.so account [default=bad success=ok user_unknown=ignore] pam_krb5.so password sufficient pam_krb5.so use_authtok session requisite pam_krb5.so
Some distributions (such as Red Hat Enterprise Linux 8) do not support the
pam_krb5.so. It is recommended to use
pam_sss.so instead, and
configure SSSD to provide Kerberos authentication.
The sandboxing used by Posit Connect involves bind mounts which map physical locations on disk onto different directory structures at runtime. Paths used by your code use these sandboxed locations. If you need to find the physical file on disk, you will need to undo the path transformation.
This section gives some examples of path rewriting and offer some ways of finding the file you need.
Let's start with an
app.R file that describes a Shiny application. This file
will be in the
apps/XX/YY/ directory underneath the
Server.DataDir location. The
YY path components correspond to the application ID and bundle (or
deployment) ID for this version of your application. This directory is
available at runtime as
The directory structure of
/opt/rstudio-connect/mnt/ is just a number of
empty directories. The "unshare" environment created during sandboxing allows
Posit Connect to associate different application directories with these
Here are some common path transformations that may be helpful. All of the
physical paths are beneath the
Server.DataDir hierarchy that
/var/lib/rstudio-connect. All of the sandbox paths are beneath
the mount directory
/opt/rstudio-connect/mnt/. This location is not
|Physical path||Sandbox Path|
Here are some actual path transformations using the default
# A source Shiny application /var/lib/rstudio-connect/apps/4/7/app.R => /opt/rstudio-connect/mnt/app/app.R # A source Plumber API /var/lib/rstudio-connect/apps/38/10/plumber.R => /opt/rstudio-connect/mnt/app/plumber.R # A source Flask API /var/lib/rstudio-connect/apps/42/12/app.py => /opt/rstudio-connect/mnt/app/app.py # A source R Markdown document /var/lib/rstudio-connect/reports/v2/8/12/temp.render.639085504/index.Rmd => /opt/rstudio-connect/mnt/app/index.Rmd # An HTML document rendered from that R Markdown document /var/lib/rstudio-connect/reports/v2/8/2/17/index.html => /opt/rstudio-connect/mnt/report/index.html # A statically deployed document /var/lib/rstudio-connect/apps/17/21/index.html => /opt/rstudio-connect/mnt/app/index.html # The Shiny package inside the packrat cache /var/lib/rstudio-connect/packrat/3.2.5/v2/library/shiny/ 28d6903a44dc53bd4823fa43ccdc08e5/shiny => /opt/rstudio-connect/mnt/packrat/3.2.5/v2/library/shiny/ 28d6903a44dc53bd4823fa43ccdc08e5/shiny # A virtual environment inside the environment cache /var/lib/rstudio-connect/python-environments/pip/3.8.12/1B2M2Y8AsgTpgAmY7PhCfg/ => /opt/rstudio-connect/mnt/python-environments/pip/3.8.12/1B2M2Y8AsgTpgAmY7PhCfg
Off-Host Execution (Public Beta)
When using off-host execution on Kubernetes, application supervisor scripts must be
present on the image that is used to execute the content. The Supervisor configuration
should be specified in the
runtimes.yaml configuration which defines the set of available content images.
For details, see our
official feature documentation.
You may need to modify the environment or resources available to processes
before the processes are launched. This can be accomplished using a program
supervisor using the
The supervisor command is provided the full target command-line, usually R or Python, which MUST be invoked by the supervisor. The process exit code from the target command MUST be returned as the exit code of the supervisor. The file descriptors for standard input, output, and error MUST NOT be intercepted by the supervisor.
The supervisor command or script must be executable by any users that may
perform package installation or run content (see next paragraph.) It must not
be located in a directory that will be masked as described in the
Sandboxing section. (If you are unsure where to put your
/usr/local/bin/ is a safe location.) If the command is not
executable, is in a disallowed directory, or does not execute its target
command-line properly, Posit Connect will log an error and fail to start.
A supervisor is executed as the appropriate
RunAs user. Package installation
always uses the
Other processes will use the content-specific
RunAs account, falling back to
Applications.RunAs if no override was configured. See the User Account for
Processes section for details.
Supervisors run within the sandbox established for any process. See the Sandboxing section for more information about process sandboxes.
Posit Connect configures the
HOME environment variables for
launched processes. Posit Connect also manages package installation and
references. Avoid altering any of this behavior in program supervisors.
Supervisor scripts must echo all informational messages to standard error to prevent Posit Connect from processing them.
You can customize the
RSTUDIO_PANDOC environment in a supervisor script or
with a content-specific environment variable.
If unset, the
RSTUDIO_PANDOC environment variable is automatically
configured as R starts. The
rmarkdown package uses this environment variable
to discover Pandoc binaries.
rmarkdown versions < 1.9 use Pandoc 1.
rmarkdown versions >= 1.9 and < 2.5
use a Pandoc 2.x before 2.11.
rmarkdown versions >= 2.5 use Pandoc 2.11+.
RSTUDIO_PANDOC setting may cause problems in some environments, as
rmarkdown package versions are compatible with all pandoc versions.
settings offer more granular control than the
This configuration uses the
nice command to lower the priority of content
execution processes. See https://man7.org/linux/man-pages/man1/nice.1.html
for details about
nice. Because process supervisors are run as a
user and not as
root or another super-user, you may not be permitted to
assign a negative (higher priority) privilege.
; /etc/rstudio-connect/rstudio-connect.gcfg [Applications] Supervisor = "/usr/bin/nice -n 2"
Applications.Supervisor setting must contain the absolute path to the
target application or script.
Example: Environment Variables#
This configuration uses a custom script to prepare a custom execution environment before finally running the target command.
; /etc/rstudio-connect/rstudio-connect.gcfg [Applications] Supervisor = "/usr/local/bin/connect-env-supervisor.sh"
Here is an example supervisor that echos its arguments, sets an environment variable, then invokes whatever arguments have been passed.
#!/usr/bin/env bash # # /usr/local/bin/connect-env-supervisor.sh # echo informational messages to standard error to # prevent Connect from processing them. echo arguments: "$@" >&2 echo >&2 export COMPANY_DATA_HOME="/data/resides/here" # Execute the target process after the environment is established. # All customization must happen before this "exec". exec "$@"
The argument list of the supervisor is the full command-line of the target
command. The supervisor MUST invoke this target command using
exec or an
Example: Script chaining#
The supervisor is a program (script) that eventually invokes the target content command. This example combines our two previous examples: it sets some environment variables and alters process priority.
; /etc/rstudio-connect/rstudio-connect.gcfg [Applications] Supervisor = "/usr/local/bin/connect-env-and-nice-supervisor.sh"
This example supervisor configures its environment then uses
nice to launch
the target command.
#!/usr/bin/env bash # # /usr/local/bin/connect-env-and-nice-supervisor.sh export COMPANY_DATA_HOME="/data/resides/here" # Execute the target process after the environment is established. # All customization must happen before this "exec". exec /usr/bin/nice -n 2 "$@"
This example uses
nice to demonstrate how your supervisor might use some
other tool to run the target process. This approach can be helpful if you have
existing tools and scripts that you want to combine into your single
If you use chaining, each command in the chain MUST invoke the next command
exec or an equivalent technique.
Your organization may use shell initialization scripts to establish a particular environment. This environment might not be completely compatible with how Posit Connect attempts to launch R and Python. We recommend building supervisor scripts gradually and carefully. Changes to the environment can alter how your content executes or even prevent R or Python from running correctly.
A configured supervisor is used to run all content in its Posit Connect environment.
- The supervisor must be readable and executable to other users (e.g.
- The supervisor must not output to standard output; use standard error.
- The supervisor must
execits target command.
- Within shell script supervisors, remember to
exportenvironment variables that need to be visible to sub-processes.
You can usually test supervisors by running them manually. For example, we can use our supervisor to run R or Python and display its version:
/usr/local/bin/connect-env-supervisor.sh \ /opt/R/3.6.3/bin/R --version
/usr/local/bin/connect-env-supervisor.sh \ /opt/Python/3.8.12/bin/python --version
We can also test arbitrary commands.
/usr/local/bin/connect-env-supervisor.sh \ /usr/bin/env echo "Hello World!"
We could also examine the environment that we expect to be established by the supervisor under different runtimes.
/usr/local/bin/connect-env-supervisor.sh \ /opt/R/3.6.3/bin/R -s -e 'Sys.getenv("COMPANY_DATA_HOME")'
/usr/local/bin/connect-env-supervisor.sh \ /opt/Python/3.8.12/bin/python -c 'import os; print(os.getenv("COMPANY_DATA_HOME"))'
config package makes it easy to
manage environment specific configuration values in R code. For example, you
might want to use one value for a variable locally, and another value when
deployed on Posit Connect. The package vignette contains more information.
The desired configuration is identified to the
config package by the
R_CONFIG_ACTIVE environment variable. The
variable is set by Connect when running content that uses R. By default
R_CONFIG_ACTIVE receives the value
rsconnect. The value that
R_CONFIG_ACTIVE receives can be changed by modifying the
setting. Note that the value of
R_CONFIG_ACTIVE is not available during
Posit Connect provides a wide variety of techniques to keep Shiny application data in the web browser synchronized. The preferred technique, and the one most widely used, is the use of WebSockets. If WebSockets are not supported, either by some intermediate network between the server and your client or by your client's web browser, then a fallback protocol will be used.
Python applications on Posit Connect that make use of WebSockets require WebSocket support from the network and any intermediate proxies.
In order of preference, the connection methods supported by R and Python Shiny applications are:
- XHR Streaming
- iframe Eventsource
- iframe HTML File
- XHR Polling
- iframe XHR Polling
- JSONP Polling
setting to disable specific protocols.
Client Protocol Selection - Shiny Applications#
To change the available protocols from the client, open a Shiny application and press the keyboard shortcut: Ctrl+Alt+Shift+A (or, from a Mac: control+option+shift+A). This will open a window that will allow you to select or deselect any of the above protocols. After you confirm the changes, these settings will be saved in your browser for future visits to this server. These settings will take effect upon loading an application hosted on this domain, and will last until you explicitly change them again; they will only have an effect on the browser in which this action was performed.