Feat/support env var on keys #164

Job	Run time
build (ubuntu-20.04, linux_openresty, t/plugin/[a-k]*)	32m 1s
build (ubuntu-20.04, linux_openresty, t/plugin/[l-z]*)	33m 10s
build (ubuntu-20.04, linux_openresty, t/admin t/cli t/config-center-yaml t/control t/core t/debug...	24m 44s
build (ubuntu-20.04, linux_openresty, t/node t/pubsub t/router t/script t/secret t/stream-node t/...	22m 29s
build (ubuntu-20.04, linux_openresty_1_19, t/plugin/[a-k]*)	29m 29s
build (ubuntu-20.04, linux_openresty_1_19, t/plugin/[l-z]*)	28m 3s
build (ubuntu-20.04, linux_openresty_1_19, t/admin t/cli t/config-center-yaml t/control t/core t/...	18m 36s
build (ubuntu-20.04, linux_openresty_1_19, t/node t/pubsub t/router t/script t/secret t/stream-no...	15m 26s
	3h 23m 58s

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