Telepresence can import environment variables from the cluster pod when running an intercept. You can then use these variables with the code running on your laptop of the service being intercepted.
There are three options available to do this:
telepresence intercept [service] --port [port] --env-file=FILENAME
This will write the environment variables to a Docker Compose
.envfile. This file can be used with
docker-composewhen starting containers locally. Please see the Docker documentation regarding the file syntax and usage for more information.
telepresence intercept [service] --port [port] --env-json=FILENAME
This will write the environment variables to a JSON file. This file can be injected into other build processes.
telepresence intercept [service] --port [port] -- [COMMAND]
This will run a command locally with the pod's environment variables set on your laptop. Once the command quits the intercept is stopped (as if
telepresence leave [service]was run). This can be used in conjunction with a local server command, such as
node [FILENAME]to run a service locally while using the environment variables that were set on the pod via a ConfigMap or other means.
Another use would be running a subshell, Bash for example:
telepresence intercept [service] --port [port] -- /bin/bash
This would start the intercept then launch the subshell on your laptop with all the same variables set as on the pod.
Telepresence adds some useful environment variables in addition to the ones imported from the intercepted pod:
Directory where all remote volumes mounts are rooted. See Volume Mounts for more info.
Colon separated list of remotely mounted directories.
The name of the intercepted container. Useful when a pod has several containers, and you want to know which one that was intercepted by Telepresence.
ID of the intercept (same as the "x-intercept-id" http header).
Useful if you need special behavior when intercepting a pod. One example might be when dealing with pub/sub systems like Kafka, where all processes that don't have the
TELEPRESENCE_INTERCEPT_ID set can filter out all messages that contain an
x-intercept-id header, while those that do, instead filter based on a matching
x-intercept-id header. This is to assure that messages belonging to a certain intercept always are consumed by the intercepting process.