语法: ngx.header.HEADER = VALUE
语法: value = ngx.header.HEADER
环境: rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*, body_filter_by_lua, log_by_lua*
修改、添加、或清除当前请求待发送的 HEADER 响应头信息。
头名称中的下划线 (_) 将被默认替换为连字符 (-)。可以通过 lua_transform_underscores_in_response_headers 指令关闭这个替换。
头名称大小写不敏感。
-- 与 ngx.header["Content-Type"] = 'text/plain' 相同
ngx.header.content_type = 'text/plain';
ngx.header["X-My-Header"] = 'blah blah';多值头信息可以按以下方法设置：
ngx.header['Set-Cookie'] = {'a=32; path=/', 'b=4; path=/'}在响应头中将输出：
Set-Cookie: a=32; path=/
Set-Cookie: b=4; path=/只接受 Lua 表输入 (对于类似 Content-Type 之类的只接受一个值的标准头信息，只有 Lua 表中的最后一个元素有效)。
ngx.header.content_type = {'a', 'b'}等同于
ngx.header.content_type = 'b'将一个头信息的值设为 nil 将从响应头中移除该输出：
ngx.header["X-My-Header"] = nil;赋值一个空 Lua 表效果相同：
ngx.header["X-My-Header"] = {};在输出响应头 (不管是显示的通过 ngx.send_headers 或隐式的通过类似 ngx.print 指令) 以后设置 ngx.header.HEADER 将抛出 Lua 异常。
读取 ngx.header.HEADER 将返回响应头中名为 HEADER 的头信息的值。
读取时，头名称中的下划线 (_) 也会被替换成连字符 (-)，并且大小写不敏感。如果该头信息不存在，将返回 nil。
这个 API 在 header_filter_by_lua 和 header_filter_by_lua_file 环境中非常有用，例如：
location /test {
set $footer '';
proxy_pass http://some-backend;
header_filter_by_lua '
if ngx.header["X-My-Header"] == "blah" then
ngx.var.footer = "some value"
end
';
echo_after_body $footer;
}对于多值头信息，所有值将被按顺序放入一个 Lua 表中，例如，响应头
Foo: bar
Foo: baz
在读取 ngx.header.Foo 时返回的结果为
{"bar", "baz"}需要注意的是，ngx.header 不是一个标准 Lua 表，不能通过 Lua 的 ipairs 函数进行迭代查询。
读取 请求 头信息，请使用 ngx.req.get_headers 函数。
English Source
syntax: ngx.header.HEADER = VALUE
syntax: value = ngx.header.HEADER
context: rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*, body_filter_by_lua, log_by_lua*
Set, add to, or clear the current request's HEADER response header that is to be sent.
Underscores (_) in the header names will be replaced by hyphens (-) by default. This transformation can be turned off via the lua_transform_underscores_in_response_headers directive.
The header names are matched case-insensitively.
-- equivalent to ngx.header["Content-Type"] = 'text/plain'
ngx.header.content_type = 'text/plain';
ngx.header["X-My-Header"] = 'blah blah';Multi-value headers can be set this way:
ngx.header['Set-Cookie'] = {'a=32; path=/', 'b=4; path=/'}will yield
Set-Cookie: a=32; path=/
Set-Cookie: b=4; path=/in the response headers.
Only Lua tables are accepted (Only the last element in the table will take effect for standard headers such as Content-Type that only accept a single value).
ngx.header.content_type = {'a', 'b'}is equivalent to
ngx.header.content_type = 'b'Setting a slot to nil effectively removes it from the response headers:
ngx.header["X-My-Header"] = nil;The same applies to assigning an empty table:
ngx.header["X-My-Header"] = {};Setting ngx.header.HEADER after sending out response headers (either explicitly with ngx.send_headers or implicitly with ngx.print and similar) will throw out a Lua exception.
Reading ngx.header.HEADER will return the value of the response header named HEADER.
Underscores (_) in the header names will also be replaced by dashes (-) and the header names will be matched case-insensitively. If the response header is not present at all, nil will be returned.
This is particularly useful in the context of header_filter_by_lua and header_filter_by_lua_file, for example,
location /test {
set $footer '';
proxy_pass http://some-backend;
header_filter_by_lua '
if ngx.header["X-My-Header"] == "blah" then
ngx.var.footer = "some value"
end
';
echo_after_body $footer;
}For multi-value headers, all of the values of header will be collected in order and returned as a Lua table. For example, response headers
Foo: bar
Foo: baz
will result in
{"bar", "baz"}to be returned when reading ngx.header.Foo.
Note that ngx.header is not a normal Lua table and as such, it is not possible to iterate through it using the Lua ipairs function.
For reading request headers, use the ngx.req.get_headers function instead.