20-envsubst-on-templates.sh: use awk to get environment.

The solution with xargs reading from /proc/self/environ is too
expensive, especially when there is a lot of environment variables to be
checked.

See https://github.com/nginxinc/docker-nginx-unprivileged/issues/107 for
more details.

entrypoint/20-envsubst-on-templates.sh

@@ -17,7 +17,7 @@ auto_envsubst() {
   local filter="${NGINX_ENVSUBST_FILTER:-}"
 
   local template defined_envs relative_path output_path subdir
-  defined_envs=$(printf '${%s} ' $(xargs -0n1 -a /proc/self/environ sh -c "echo \"\$@\" | grep -- \"${filter}\" | grep -oEm1 \"^[^=]+\"" --));
+  defined_envs=$(printf '${%s} ' $(awk "END { for (name in ENVIRON) { print ( name ~ /${filter}/ ) ? name : \"\" } }" < /dev/null ))
   [ -d "$template_dir" ] || return 0
   if [ ! -w "$output_dir" ]; then
     entrypoint_log "$ME: ERROR: $template_dir exists, but $output_dir is not writable"

mainline/alpine-perl/20-envsubst-on-templates.sh

@@ -17,7 +17,7 @@ auto_envsubst() {
   local filter="${NGINX_ENVSUBST_FILTER:-}"
 
   local template defined_envs relative_path output_path subdir
-  defined_envs=$(printf '${%s} ' $(xargs -0n1 -a /proc/self/environ sh -c "echo \"\$@\" | grep -- \"${filter}\" | grep -oEm1 \"^[^=]+\"" --));
+  defined_envs=$(printf '${%s} ' $(awk "END { for (name in ENVIRON) { print ( name ~ /${filter}/ ) ? name : \"\" } }" < /dev/null ))
   [ -d "$template_dir" ] || return 0
   if [ ! -w "$output_dir" ]; then
     entrypoint_log "$ME: ERROR: $template_dir exists, but $output_dir is not writable"

mainline/alpine-slim/20-envsubst-on-templates.sh

@@ -17,7 +17,7 @@ auto_envsubst() {
   local filter="${NGINX_ENVSUBST_FILTER:-}"
 
   local template defined_envs relative_path output_path subdir
-  defined_envs=$(printf '${%s} ' $(xargs -0n1 -a /proc/self/environ sh -c "echo \"\$@\" | grep -- \"${filter}\" | grep -oEm1 \"^[^=]+\"" --));
+  defined_envs=$(printf '${%s} ' $(awk "END { for (name in ENVIRON) { print ( name ~ /${filter}/ ) ? name : \"\" } }" < /dev/null ))
   [ -d "$template_dir" ] || return 0
   if [ ! -w "$output_dir" ]; then
     entrypoint_log "$ME: ERROR: $template_dir exists, but $output_dir is not writable"

mainline/alpine/20-envsubst-on-templates.sh

@@ -17,7 +17,7 @@ auto_envsubst() {
   local filter="${NGINX_ENVSUBST_FILTER:-}"
 
   local template defined_envs relative_path output_path subdir
-  defined_envs=$(printf '${%s} ' $(xargs -0n1 -a /proc/self/environ sh -c "echo \"\$@\" | grep -- \"${filter}\" | grep -oEm1 \"^[^=]+\"" --));
+  defined_envs=$(printf '${%s} ' $(awk "END { for (name in ENVIRON) { print ( name ~ /${filter}/ ) ? name : \"\" } }" < /dev/null ))
   [ -d "$template_dir" ] || return 0
   if [ ! -w "$output_dir" ]; then
     entrypoint_log "$ME: ERROR: $template_dir exists, but $output_dir is not writable"

mainline/debian-perl/20-envsubst-on-templates.sh

@@ -17,7 +17,7 @@ auto_envsubst() {
   local filter="${NGINX_ENVSUBST_FILTER:-}"
 
   local template defined_envs relative_path output_path subdir
-  defined_envs=$(printf '${%s} ' $(xargs -0n1 -a /proc/self/environ sh -c "echo \"\$@\" | grep -- \"${filter}\" | grep -oEm1 \"^[^=]+\"" --));
+  defined_envs=$(printf '${%s} ' $(awk "END { for (name in ENVIRON) { print ( name ~ /${filter}/ ) ? name : \"\" } }" < /dev/null ))
   [ -d "$template_dir" ] || return 0
   if [ ! -w "$output_dir" ]; then
     entrypoint_log "$ME: ERROR: $template_dir exists, but $output_dir is not writable"

mainline/debian/20-envsubst-on-templates.sh

@@ -17,7 +17,7 @@ auto_envsubst() {
   local filter="${NGINX_ENVSUBST_FILTER:-}"
 
   local template defined_envs relative_path output_path subdir
-  defined_envs=$(printf '${%s} ' $(xargs -0n1 -a /proc/self/environ sh -c "echo \"\$@\" | grep -- \"${filter}\" | grep -oEm1 \"^[^=]+\"" --));
+  defined_envs=$(printf '${%s} ' $(awk "END { for (name in ENVIRON) { print ( name ~ /${filter}/ ) ? name : \"\" } }" < /dev/null ))
   [ -d "$template_dir" ] || return 0
   if [ ! -w "$output_dir" ]; then
     entrypoint_log "$ME: ERROR: $template_dir exists, but $output_dir is not writable"

stable/alpine-perl/20-envsubst-on-templates.sh

@@ -17,7 +17,7 @@ auto_envsubst() {
   local filter="${NGINX_ENVSUBST_FILTER:-}"
 
   local template defined_envs relative_path output_path subdir
-  defined_envs=$(printf '${%s} ' $(xargs -0n1 -a /proc/self/environ sh -c "echo \"\$@\" | grep -- \"${filter}\" | grep -oEm1 \"^[^=]+\"" --));
+  defined_envs=$(printf '${%s} ' $(awk "END { for (name in ENVIRON) { print ( name ~ /${filter}/ ) ? name : \"\" } }" < /dev/null ))
   [ -d "$template_dir" ] || return 0
   if [ ! -w "$output_dir" ]; then
     entrypoint_log "$ME: ERROR: $template_dir exists, but $output_dir is not writable"

stable/alpine-slim/20-envsubst-on-templates.sh

@@ -17,7 +17,7 @@ auto_envsubst() {
   local filter="${NGINX_ENVSUBST_FILTER:-}"
 
   local template defined_envs relative_path output_path subdir
-  defined_envs=$(printf '${%s} ' $(xargs -0n1 -a /proc/self/environ sh -c "echo \"\$@\" | grep -- \"${filter}\" | grep -oEm1 \"^[^=]+\"" --));
+  defined_envs=$(printf '${%s} ' $(awk "END { for (name in ENVIRON) { print ( name ~ /${filter}/ ) ? name : \"\" } }" < /dev/null ))
   [ -d "$template_dir" ] || return 0
   if [ ! -w "$output_dir" ]; then
     entrypoint_log "$ME: ERROR: $template_dir exists, but $output_dir is not writable"

stable/alpine/20-envsubst-on-templates.sh

@@ -17,7 +17,7 @@ auto_envsubst() {
   local filter="${NGINX_ENVSUBST_FILTER:-}"
 
   local template defined_envs relative_path output_path subdir
-  defined_envs=$(printf '${%s} ' $(xargs -0n1 -a /proc/self/environ sh -c "echo \"\$@\" | grep -- \"${filter}\" | grep -oEm1 \"^[^=]+\"" --));
+  defined_envs=$(printf '${%s} ' $(awk "END { for (name in ENVIRON) { print ( name ~ /${filter}/ ) ? name : \"\" } }" < /dev/null ))
   [ -d "$template_dir" ] || return 0
   if [ ! -w "$output_dir" ]; then
     entrypoint_log "$ME: ERROR: $template_dir exists, but $output_dir is not writable"

stable/debian-perl/20-envsubst-on-templates.sh

@@ -17,7 +17,7 @@ auto_envsubst() {
   local filter="${NGINX_ENVSUBST_FILTER:-}"
 
   local template defined_envs relative_path output_path subdir
-  defined_envs=$(printf '${%s} ' $(xargs -0n1 -a /proc/self/environ sh -c "echo \"\$@\" | grep -- \"${filter}\" | grep -oEm1 \"^[^=]+\"" --));
+  defined_envs=$(printf '${%s} ' $(awk "END { for (name in ENVIRON) { print ( name ~ /${filter}/ ) ? name : \"\" } }" < /dev/null ))
   [ -d "$template_dir" ] || return 0
   if [ ! -w "$output_dir" ]; then
     entrypoint_log "$ME: ERROR: $template_dir exists, but $output_dir is not writable"

stable/debian/20-envsubst-on-templates.sh

@@ -17,7 +17,7 @@ auto_envsubst() {
   local filter="${NGINX_ENVSUBST_FILTER:-}"
 
   local template defined_envs relative_path output_path subdir
-  defined_envs=$(printf '${%s} ' $(xargs -0n1 -a /proc/self/environ sh -c "echo \"\$@\" | grep -- \"${filter}\" | grep -oEm1 \"^[^=]+\"" --));
+  defined_envs=$(printf '${%s} ' $(awk "END { for (name in ENVIRON) { print ( name ~ /${filter}/ ) ? name : \"\" } }" < /dev/null ))
   [ -d "$template_dir" ] || return 0
   if [ ! -w "$output_dir" ]; then
     entrypoint_log "$ME: ERROR: $template_dir exists, but $output_dir is not writable"