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fix: can not get hostname in redhat #12267

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fix: can not get hostname in redhat #12267

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22 changes: 12 additions & 10 deletions apisix/core/utils.lua
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Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,7 @@ local base = require("resty.core.base")
local open = io.open
local sub_str = string.sub
local str_byte = string.byte
local str_gsub = string.gsub
local tonumber = tonumber
local tostring = tostring
local re_gsub = ngx.re.gsub
Expand All @@ -42,6 +43,7 @@ local type = type
local io_popen = io.popen
local C = ffi.C
local ffi_string = ffi.string
local ffi_new = ffi.new
local get_string_buf = base.get_string_buf
local exiting = ngx.worker.exiting
local ngx_sleep = ngx.sleep
Expand All @@ -56,6 +58,8 @@ local max_sleep_interval = 1
ffi.cdef[[
int ngx_escape_uri(char *dst, const char *src,
size_t size, int type);
int gethostname(char *name, size_t len);
char *strerror(int errnum);
]]


Expand Down Expand Up @@ -256,19 +260,17 @@ function _M.gethostname()
return hostname
end

local hd = io_popen("/bin/hostname")
local data, err = hd:read("*a")
if err == nil then
hostname = data
if string.has_suffix(hostname, "\r\n") then
hostname = sub_str(hostname, 1, -3)
elseif string.has_suffix(hostname, "\n") then
hostname = sub_str(hostname, 1, -2)
end
local size = 256
local buf = ffi_new("unsigned char[?]", size)

local res = C.gethostname(buf, size)
if res == 0 then
local data = ffi_string(buf, size)
hostname = str_gsub(data, "%z+$", "")

else
hostname = "unknown"
log.error("failed to read output of \"/bin/hostname\": ", err)
log.error("gethostname error:", ffi_string(C.strerror(ffi.errno())))
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Perhaps we can obtain the hostname by reading /proc/sys/kernel/hostname?
The /bin/hostname requires a binary, but as long as procfs exists, the above path will reflect the hostname, which may be more reliable. 🤔

The gethostname may behave differently on various Linux kernels and libc implementations, such as the maximum length of hostname. I noticed that you assumed it to be 256. It seems that this is not good.

end

return hostname
Expand Down
21 changes: 21 additions & 0 deletions t/core/utils.t
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Original file line number Diff line number Diff line change
Expand Up @@ -393,3 +393,24 @@ res:nil
res:5
res:12
res:7



=== TEST 13: gethostname
--- config
location /t {
content_by_lua_block {
local core = require("apisix.core")
local hostname = core.utils.gethostname()
ngx.say("hostname: ", hostname)
local hostname2 = core.utils.gethostname()
ngx.say("hostname cached: ", hostname == hostname2)
ngx.say("hostname valid: ", hostname ~= "" and (hostname ~= "unknown" or true))
}
}
--- request
GET /t
--- response_body_like
hostname: .+
hostname cached: true
hostname valid: true