本文分享自天翼云开发者社区《
ngx.location.capture()变量继承》.作者：lucky_lyw
通过几个例子，简要分析variable与ctx在主请求与子请求中的关系。
copy_all_vars & share_all vars
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server {
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listen [::]:80; #https配置-http访问端口v6格式
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listen 80; #https配置-http访问端口v4格式
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#listen [::]:443 ssl; #https配置-https访问端口v6格式
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#listen 443 ssl; #https配置-https访问端口v4格式
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#ssl_certificate ssl/vsochina.com.crt;
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#ssl_certificate_key ssl/vsochina.com.key
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# ssl_certificate conf.d/common/ssl/vsochina.com.crt;
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#ssl_certificate_key conf.d/common/ssl/vsochina.com.key
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server_name www.l.com;
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location /static {
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root /root/resources/;
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}
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location /sub {
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content_by_lua_block {
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ngx.log(ngx.ERR, "sub: ", ngx.var.dysta)
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ngx.var.dysta = "luoyuwen"
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ngx.log(ngx.ERR, "sub: ", ngx.var.dysta)
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}
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}
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location /main {
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content_by_lua_block {
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ngx.var.dysta="luoluo"
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ngx.log(ngx.ERR, "main: ", ngx.var.dysta)
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res = ngx.location.capture("/sub", {copy_all_vars=true})
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ngx.log(ngx.ERR, "main: ", ngx.var.dysta)
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res = ngx.location.capture("/sub", {share_all_vars=true})
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ngx.log(ngx.ERR, "sub: ", ngx.var.dysta)
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}
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}
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}
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2022/07/12 14:07:42 [error] 770#0: *6 [lua] content_by_lua(www.l.com.conf:34):3: main: luoluo, client: 127.0.0.1, server: www.l.com, request: "GET /main HTTP/1.1", host: ""
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2022/07/12 14:07:42 [error] 770#0: *6 [lua] content_by_lua(www.l.com.conf:23):2: sub: luoluo, client: 127.0.0.1, server: www.l.com, request: "GET /main HTTP/1.1", subrequest: "/sub", host: ""
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2022/07/12 14:07:42 [error] 770#0: *6 [lua] content_by_lua(www.l.com.conf:23):4: sub: luoyuwen, client: 127.0.0.1, server: www.l.com, request: "GET /main HTTP/1.1", subrequest: "/sub", host: ""
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2022/07/12 14:07:42 [error] 770#0: *6 [lua] content_by_lua(www.l.com.conf:34):5: main: luoluo, client: 127.0.0.1, server: www.l.com, request: "GET /main HTTP/1.1", host: ""
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2022/07/12 14:07:42 [error] 770#0: *6 [lua] content_by_lua(www.l.com.conf:23):2: sub: luoluo, client: 127.0.0.1, server: www.l.com, request: "GET /main HTTP/1.1", subrequest: "/sub", host: ""
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2022/07/12 14:07:42 [error] 770#0: *6 [lua] content_by_lua(www.l.com.conf:23):4: sub: luoyuwen, client: 127.0.0.1, server: www.l.com, request: "GET /main HTTP/1.1", subrequest: "/sub", host: ""
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2022/07/12 14:07:42 [error] 770#0: *6 [lua] content_by_lua(www.l.com.conf:34):7: sub: luoyuwen, client: 127.0.0.1, server: www.l.com, request: "GET /main HTTP/1.1", host: ""
结论：
copy仅赋值，share共享
ctx
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location /sub {
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content_by_lua_block {
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ngx.log(ngx.ERR, "sub: ", ngx.ctx.foo)
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ngx.ctx.foo = "bar"
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ngx.log(ngx.ERR, "sub: ", ngx.ctx.foo)
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}
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}
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location /main {
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content_by_lua_block {
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ngx.ctx.foo = "luoluo"
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local ctx = {}
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ctx.foo = "mm"
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ngx.log(ngx.ERR, "main: ", ngx.ctx.foo)
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res = ngx.location.capture("/sub", {ctx=ctx})
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ngx.log(ngx.ERR, "main: ", ngx.ctx.foo)
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ngx.log(ngx.ERR, "main: ", ctx.foo)
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}
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}
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2022/07/12 13:56:11 [error] 770#0: *4 [lua] content_by_lua(www.l.com.conf:35):5: main: luoluo, client: 127.0.0.1, server: www.l.com, request: "GET /main HTTP/1.1", host: ""
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2022/07/12 13:56:11 [error] 770#0: *4 [lua] content_by_lua(www.l.com.conf:23):2: sub: mm, client: 127.0.0.1, server: www.l.com, request: "GET /main HTTP/1.1", subrequest: "/sub", host: ""
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2022/07/12 13:56:11 [error] 770#0: *4 [lua] content_by_lua(www.l.com.conf:23):4: sub: bar, client: 127.0.0.1, server: www.l.com, request: "GET /main HTTP/1.1", subrequest: "/sub", host: ""
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2022/07/12 13:56:11 [error] 770#0: *4 [lua] content_by_lua(www.l.com.conf:35):7: main: luoluo, client: 127.0.0.1, server: www.l.com, request: "GET /main HTTP/1.1", host: ""
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2022/07/12 13:56:11 [error] 770#0: *4 [lua] content_by_lua(www.l.com.conf:35):8: main: bar, client: 127.0.0.1, server: www.l.com, request: "GET /main HTTP/1.1", host: ""
结论：
主请求与子请求中的ctx可以赋值并相互影响。
ngx.location.capture("/uri", {ctx_a = ctx_b})
ctx_a为子请求中的ngx.ctx，ctx_b为主请求中的ctx_b, 若该值为ngx.ctx，则为主请求中的ngx.ctx。
首先，将ctx_b赋值给子请求中的ngx.ctx。
子请求中可查询ngx.ctx，其值为主请求的ctx_b
若在子请求中更改ngx.ctx，则会映射到主请求中的ctx_b
