feat: implement templating for the PROXY_CACHE_USE_STALE env var (#450)

* feat: implement templating for the `PROXY_CACHE_USE_STALE` env var

Fixes #437

This change modifies the startup scripts to support the optional
parameter `PROXY_CACHE_USE_STALE` which corresponds to the
NGINX directive with the same name. When this environment
variable is not set, a default is used.

Signed-off-by: Elijah Zupancic <[email protected]>
Co-Authored-By: Elijah Zupancic <[email protected]>

* Update common/docker-entrypoint.d/00-check-for-required-env.sh

Co-authored-by: Copilot <[email protected]>

* Update docs/getting_started.md

Co-authored-by: Copilot <[email protected]>

* Update common/docker-entrypoint.d/00-check-for-required-env.sh

Co-authored-by: Copilot <[email protected]>

---------

Signed-off-by: Elijah Zupancic <[email protected]>
Co-authored-by: MohammadHosein Bahmani <[email protected]>
Co-authored-by: Copilot <[email protected]>

Author: 3 people

common/docker-entrypoint.d/00-check-for-required-env.sh

@@ -144,6 +144,7 @@ echo "Directory Listing Path Prefix: ${DIRECTORY_LISTING_PATH_PREFIX}"
 echo "Provide Index Pages Enabled: ${PROVIDE_INDEX_PAGE}"
 echo "Append slash for directory enabled: ${APPEND_SLASH_FOR_POSSIBLE_DIRECTORY}"
 echo "Stripping the following headers from responses: x-amz-;${HEADER_PREFIXES_TO_STRIP}"
-echo "Allow the following headers from responses (these take precendence over the above): ${HEADER_PREFIXES_ALLOWED}"
+echo "Allow the following headers from responses (these take precedence over the above): ${HEADER_PREFIXES_ALLOWED}"
 echo "CORS Enabled: ${CORS_ENABLED}"
 echo "CORS Allow Private Network Access: ${CORS_ALLOW_PRIVATE_NETWORK_ACCESS}"
+echo "Proxy cache using stale setting: ${PROXY_CACHE_USE_STALE}"

common/docker-entrypoint.sh

@@ -94,6 +94,10 @@ else
   export S3_HOST_HEADER="${S3_BUCKET_NAME}.${S3_SERVER}"
 fi
 
+# Use default proxy_cache_use_stale settings if the variable is not defined
+if [[ ! -v PROXY_CACHE_USE_STALE ]]; then
+  export PROXY_CACHE_USE_STALE="error timeout http_500 http_502 http_503 http_504"
+fi
 
 # Nothing is modified under this line
 

common/etc/nginx/nginx.conf

@@ -38,6 +38,7 @@ env PROXY_CACHE_VALID_OK;
 env PROXY_CACHE_SLICE_SIZE;
 env PROXY_CACHE_VALID_NOTFOUND;
 env PROXY_CACHE_VALID_FORBIDDEN;
+env PROXY_CACHE_USE_STALE;
 env HEADER_PREFIXES_TO_STRIP;
 env FOUR_O_FOUR_ON_EMPTY_BUCKET;
 env STRIP_LEADING_DIRECTORY_PATH;

common/etc/nginx/templates/default.conf.template

@@ -56,7 +56,7 @@ server {
     proxy_cache_revalidate on;
     proxy_cache_background_update on;
     proxy_cache_lock on;
-    proxy_cache_use_stale error timeout http_500 http_502 http_503 http_504;
+    proxy_cache_use_stale ${PROXY_CACHE_USE_STALE};
     proxy_cache_key "$request_method$host$uri";
 
     # If you need to support proxying range request, refer to this article:

deployments/s3_express/settings.s3express.example

@@ -20,3 +20,4 @@ PROXY_CACHE_INACTIVE=60m
 PROXY_CACHE_VALID_OK=1h
 PROXY_CACHE_VALID_NOTFOUND=1m
 PROXY_CACHE_VALID_FORBIDDEN=30s
+PROXY_CACHE_USE_STALE='error timeout http_500 http_502 http_503 http_504'

docs/getting_started.md

@@ -20,4 +20,5 @@ PROXY_CACHE_INACTIVE=60m
 PROXY_CACHE_VALID_OK=1h
 PROXY_CACHE_VALID_NOTFOUND=1m
 PROXY_CACHE_VALID_FORBIDDEN=30s
+PROXY_CACHE_USE_STALE='error timeout http_500 http_502 http_503 http_504'
 STRIP_LEADING_DIRECTORY_PATH=/somepath

settings.example

@@ -96,6 +96,7 @@ echo "Slice of slice for byte range requests: ${PROXY_CACHE_SLICE_SIZE}"
 echo "Proxy Caching Time for Valid Response: ${PROXY_CACHE_VALID_OK}"
 echo "Proxy Caching Time for Not Found Response: ${PROXY_CACHE_VALID_NOTFOUND}"
 echo "Proxy Caching Time for Forbidden Response: ${PROXY_CACHE_VALID_FORBIDDEN}"
+echo "Proxy Cache Using Stale: ${PROXY_CACHE_USE_STALE}"
 echo "CORS Enabled: ${CORS_ENABLED}"
 echo "CORS Allow Private Network Access: ${CORS_ALLOW_PRIVATE_NETWORK_ACCESS}"
 
@@ -179,6 +180,8 @@ PROXY_CACHE_VALID_OK=${PROXY_CACHE_VALID_OK:-'1h'}
 PROXY_CACHE_VALID_NOTFOUND=${PROXY_CACHE_VALID_NOTFOUND:-'1m'}
 # Proxy caching time for response code 403
 PROXY_CACHE_VALID_FORBIDDEN=${PROXY_CACHE_VALID_FORBIDDEN:-'30s'}
+# Proxy cache using stale data when error occurs
+PROXY_CACHE_USE_STALE=${PROXY_CACHE_USE_STALE:-'error timeout http_500 http_502 http_503 http_504'}
 # Enables or disables CORS for the S3 Gateway (true=enabled, false=disabled)
 CORS_ENABLED=${CORS_ENABLED:-'false'}
 # Configure portion of URL to be removed (optional)