tests: Skip AWS ECR login outside of CI jobs

To avoid rate limiting errors, CI (currently Azure Devops) logs into the
container registry (currently AWS ECR). Outside CI this is unnnecessary and
makes it harder to run the tests, because very few people have access to a
suitable AWS secret token.

Following this change `aws ecr-public get-login-password` will only be run if
the environment variable $TF_BUILD==True. This is set by Azure Pipelines
jobs. If the CI platform is changed then another indicator should be used.

https://adamj.eu/tech/2020/03/09/detect-if-your-tests-are-running-on-ci/

.ci/ansible_install.py

@@ -4,7 +4,7 @@ import ci_lib
 
 batches = [
     [
-        'aws ecr-public get-login-password | docker login --username AWS --password-stdin public.ecr.aws',
+        'if [ "${TF_BUILD:-false}" = "True" ]; then aws ecr-public get-login-password | docker login --username AWS --password-stdin public.ecr.aws; fi',
     ]
 ]
 

.ci/debops_common_install.py

@@ -10,7 +10,7 @@ ci_lib.run_batches([
         'python -m pip --no-python-version-warning --disable-pip-version-check "debops[ansible]==2.1.2"',
     ],
     [
-        'aws ecr-public get-login-password | docker login --username AWS --password-stdin public.ecr.aws',
+        'if [ "${TF_BUILD:-false}" = "True" ]; then aws ecr-public get-login-password | docker login --username AWS --password-stdin public.ecr.aws; fi',
     ],
 ])
 

.ci/mitogen_install.py

@@ -7,7 +7,7 @@ batches = [
 
 if ci_lib.have_docker():
     batches.append([
-        'aws ecr-public get-login-password | docker login --username AWS --password-stdin public.ecr.aws',
+        'if [ "${TF_BUILD:-false}" = "True" ]; then aws ecr-public get-login-password | docker login --username AWS --password-stdin public.ecr.aws; fi',
     ])
 
 

.ci/mitogen_py24_install.py

@@ -4,7 +4,7 @@ import ci_lib
 
 batches = [
     [
-        'aws ecr-public get-login-password | docker login --username AWS --password-stdin public.ecr.aws',
+        'if [ "${TF_BUILD:-false}" = "True" ]; then aws ecr-public get-login-password | docker login --username AWS --password-stdin public.ecr.aws; fi',
     ],
     [
         'curl https://dw.github.io/mitogen/binaries/ubuntu-python-2.4.6.tar.bz2 | sudo tar -C / -jxv',

tox.ini

@@ -104,6 +104,9 @@ passenv =
     AWS_DEFAULT_REGION
     AWS_SECRET_ACCESS_KEY
     HOME
+    # Azure DevOps, TF_BUILD is set to 'True' when running in a build task
+    # https://learn.microsoft.com/en-us/azure/devops/pipelines/build/variables
+    TF_BUILD
 setenv =
     # See also azure-pipelines.yml
     ANSIBLE_STRATEGY = mitogen_linear