Explain more about Docker and proxies

KNOWLEDGE.md

@@ -57,6 +57,21 @@ E: Release file for http://security.debian.org/debian-security/dists/buster/upda
 E: Release file for http://deb.debian.org/debian/dists/buster-updates/InRelease is not valid yet (invalid for another 17h 37min 38s). Updates for this repository will not be applied.
 ```
 
+### Docker and proxies
+
+Docker Compose does automatically set http_proxy, HTTP_PROXY, https_proxy,
+HTTPS_PROXY, no_proxy and NO_PROXY with the values specified in
+~/.docker/config.json. Unfortunately Docker Swarm does not set those value,
+but those can be set by using environment variables, e.g. using an env file.
+The proxy variables by the env file do overwrite the settings of config.json.
+To make the proxy only available during building an image, but not when the
+container runs (in Compose as in Swarm this is never the case), then set proxy
+in config.json, but explicitly reset them in the env file. This seems to be
+necessary as Playwright doesn't respect the no_proxy setup and may lead to
+strange errors during integration testing.
+See also <https://docs.docker.com/network/proxy/#configure-the-docker-client>
+and <https://forums.docker.com/t/docker-swarm-mode-not-picking-up-proxy-configuration/132233/8?u=medihack>
+
 ## Gitpod
 
 - It is not possible to set an ENV variable using the Gitpod Dockerfile

example.env

@@ -25,20 +25,9 @@ SSL_IP_ADDRESSES=127.0.0.1
 USER_TIME_ZONE=Europe/Berlin
 FORCE_DEBUG_TOOLBAR=false
 BACKUP_DIR=/mnt/backups
-
-# Docker Compose does automatically set http_proxy, HTTP_PROXY, https_proxy,
-# HTTPS_PROXY, no_proxy and NO_PROXY with the values specified in
-# ~/.docker/config.json. Unfortunately Docker Swarm does not set those value,
-# but those can be set by the environment variables in the env file.
-# If those are set in Docker Compose mode the ones here overwrite those
-# in the config.json file.
-# Cave, those variables here doesn't have any effect when the image is build
-# (only those in the config.json file work).
-# See also https://docs.docker.com/network/proxy/#configure-the-docker-client
-# and https://forums.docker.com/t/docker-swarm-mode-not-picking-up-proxy-configuration/132233/8?u=medihack
-# http_proxy=http://user:pass@myproxy.net:8080
-# HTTP_PROXY=http://user:pass@myproxy.net:8080
-# https_proxy=http://user:pass@myproxy.net:8080
-# HTTPS_PROXY=http://user:pass@myproxy.net:8080
-# no_proxy=
-# NO_PROXY=
+http_proxy=
+HTTP_PROXY=
+https_proxy=
+HTTPS_PROXY=
+no_proxy=
+NO_PROXY=