Merge bitcoin/bitcoin#27976: ci: Start with clean env

fa15f7e ci: Remove no longer applicable section (MarcoFalke)
fa378be ci: Start with clean env (MarcoFalke)
fa8c250 ci: Limit scope of some env vars (MarcoFalke)

Pull request description:

  Starting with a clean `env` should help to avoid non-determinism, such as the one fixed in bitcoin/bitcoin#27739 (comment)

ACKs for top commit:
  dergoegge:
    utACK fa15f7e

Tree-SHA512: 716b264217557b6524dab92d5a2a8d61ecb982dff475bd0cf5a763070b4c5916cd5995e764eb5d67d9cf2428c29d5fc2f42b32941b54c7c3053123ce448171e5

ci/README.md

@@ -20,10 +20,11 @@ requires `bash`, `docker`, and `python3` to be installed. To install all require
 sudo apt install bash docker.io python3
 ```
 
-To run the test stage with a specific configuration,
+It is recommended to run the ci system in a clean env. To run the test stage
+with a specific configuration,
 
 ```
-FILE_ENV="./ci/test/00_setup_env_arm.sh" ./ci/test_run_all.sh
+env -i HOME="$HOME" PATH="$PATH" USER="$USER" bash -c 'FILE_ENV="./ci/test/00_setup_env_arm.sh" ./ci/test_run_all.sh'
 ```
 
 ### Configurations
@@ -38,14 +39,11 @@ the system package manager to install build dependencies. This guarantees that
 the tester is using the same versions as the release builds, which also use
 `./depends`.
 
-If no `FILE_ENV` has been specified or values are left out, `00_setup_env.sh`
-is used as the default configuration with fallback values.
-
 It is also possible to force a specific configuration without modifying the
 file. For example,
 
 ```
-MAKEJOBS="-j1" FILE_ENV="./ci/test/00_setup_env_arm.sh" ./ci/test_run_all.sh
+env -i HOME="$HOME" PATH="$PATH" USER="$USER" bash -c 'MAKEJOBS="-j1" FILE_ENV="./ci/test/00_setup_env_arm.sh" ./ci/test_run_all.sh'
 ```
 
 The files starting with `0n` (`n` greater than 0) are the scripts that are run

ci/test/00_setup_env.sh

@@ -67,7 +67,6 @@ export BASE_BUILD_DIR=${BASE_BUILD_DIR:-$BASE_SCRATCH_DIR/build}
 # The folder for previous release binaries.
 # This folder exists only on the ci guest, and on the ci host as a volume.
 export PREVIOUS_RELEASES_DIR=${PREVIOUS_RELEASES_DIR:-$BASE_ROOT_DIR/prev_releases}
-export SDK_URL=${SDK_URL:-https://bitcoincore.org/depends-sources/sdks}
 export CI_BASE_PACKAGES=${CI_BASE_PACKAGES:-build-essential libtool autotools-dev automake pkg-config bsdmainutils curl ca-certificates ccache python3 rsync git procps bison}
 export GOAL=${GOAL:-install}
 export DIR_QA_ASSETS=${DIR_QA_ASSETS:-${BASE_SCRATCH_DIR}/qa-assets}

ci/test/00_setup_env_mac.sh

@@ -6,6 +6,8 @@
 
 export LC_ALL=C.UTF-8
 
+export SDK_URL=${SDK_URL:-https://bitcoincore.org/depends-sources/sdks}
+
 export CONTAINER_NAME=ci_macos_cross
 export CI_IMAGE_NAME_TAG=ubuntu:22.04
 export HOST=x86_64-apple-darwin

ci/test/04_install.sh

@@ -6,11 +6,6 @@
 
 export LC_ALL=C.UTF-8
 
-export ASAN_OPTIONS="detect_stack_use_after_return=1:check_initialization_order=1:strict_init_order=1"
-export LSAN_OPTIONS="suppressions=${BASE_ROOT_DIR}/test/sanitizer_suppressions/lsan"
-export TSAN_OPTIONS="suppressions=${BASE_ROOT_DIR}/test/sanitizer_suppressions/tsan:halt_on_error=1:log_path=${BASE_SCRATCH_DIR}/sanitizer-output/tsan"
-export UBSAN_OPTIONS="suppressions=${BASE_ROOT_DIR}/test/sanitizer_suppressions/ubsan:print_stacktrace=1:halt_on_error=1:report_error_type=1"
-
 if [ -z "$DANGER_RUN_CI_ON_HOST" ]; then
   # Export all env vars to avoid missing some.
   # Though, exclude those with newlines to avoid parsing problems.

ci/test/06_script_b.sh

@@ -8,6 +8,11 @@ export LC_ALL=C.UTF-8
 
 set -ex
 
+export ASAN_OPTIONS="detect_stack_use_after_return=1:check_initialization_order=1:strict_init_order=1"
+export LSAN_OPTIONS="suppressions=${BASE_ROOT_DIR}/test/sanitizer_suppressions/lsan"
+export TSAN_OPTIONS="suppressions=${BASE_ROOT_DIR}/test/sanitizer_suppressions/tsan:halt_on_error=1:log_path=${BASE_SCRATCH_DIR}/sanitizer-output/tsan"
+export UBSAN_OPTIONS="suppressions=${BASE_ROOT_DIR}/test/sanitizer_suppressions/ubsan:print_stacktrace=1:halt_on_error=1:report_error_type=1"
+
 if [ "$CI_OS_NAME" == "macos" ]; then
   top -l 1 -s 0 | awk ' /PhysMem/ {print}'
   echo "Number of CPUs: $(sysctl -n hw.logicalcpu)"